Process of and apparatus for use in drying ores, concentrates, and other granular materials



G. RlGG ET AL PROCESS 0F AND APPARATUS FOR USE IN' DRYING ORES,CONCENTRATES,

` AND OTHER GRANULAR MATERIALS EN 5M Oa. 6, 1925. v 1,556,250

G. RIG@ E1- Al. PROCESS 0F AND APPARATUS FOR-USE IN DRYING ORES,CONCENTRATES,

AND OTHER GRANULAR MATERIALS Filed July 11, 1922 3 Sheets-Sheet 2 on. e,1925. 1,556,250

G. RIGG ET AL .PROCESS OFAND APPARATUS FOR Use: IN DRYING GRES,CONCENTRATES,

AND OTHER GRANULAR MATERIALS Filed Jul-y 1l. v1922 3 Sheets-Sheet sPassed oa. e, 1925..

1li-UNITED STATES- 1,sss,zso

PATENT oFFlca.

GILBBT MELBOURNE, VICTORIA, AND il'. MO'BBIDE, OF BROKEN I HILL, NEWSOUTH WALES, AUSTRALIA.

PROCESS Ol' AIND APPARATUS-FOR USE`INDRYING DRES, CONCENTRATES, ANDOTHER GRANULAR MATERIALS.

. Appuauon mea July 11, 1922. serial No. 574,215.

To all twhom t may' concern: c

Be it known that GILBERT Rice, of care of 'The Broken Hill AssociatedProprietary Limited, of Collins House, S60-366 Collins Street,Melbourne, in the State lof Victoria, and WILLIAM JOHN Mc- Bnmn, of careof The Broken Hill South ,Limited of Broken Hill, innthe State of NewSouth Wales, both in .the Commonwealth of Australia,metallurgists,,hav'e invented certain new and useful Improve- 'ments inProcesses of and Apparatus vfor Use in Drying Orcs, Concentrates, andOther Granular Materials; and we do hereby declare the following to be afull, clear, and exact description of the invention, -such as willenable others skilled in the art to which s l'it appertainsto make anduse the same.

This invention relates toa process of Aand apparatus for use '1n drying.ores, concen-L trates, and other granular materials, and 'refersmoreespecially to processeswherein a hotblaster draught of heated vair,-or vof.a -to carry of moisture from the materials being dried.

"The invention may beemployed for drying' or4v dehydrating differentlkindsV ofgranular material and .throughout the following-f.specification, v, wherever 'the yterm oresfis'used'it is to -beunderstood as meaning and-including other granular materials.'The'object of the invention is to .provide v Ameans whereby granularmaterial inl a damp "form can be eiiiciently and expeditiously dried ordehydrated in an economical and' convenient manner.

We accomplish the object of this inventionby providing a process. ofdrying ores -which consists of forming a layer of thewet or dampmaterial on a porous bed, drawing `or forcing hot gases through the saidlayer and porous bed, drawing oli' the moisture with the hbt gases, andfinally drawing'the dried or dehydrated material through the said porousbed.

In practice, we provide a layer of the material to'be dried,supported'or-imposed on a porous bed through which hot gases Smeltersare drawn. The bed is of such a nature dry. The interstices of the saidporousbed are such as to offer' a certain resistance to the passage ofthe gases, thus assisting to maintain even conditions of draught throughthe The process may be operated continuously or intermittently. Whenoperating continuously, the ore may be caused to progress on aperforatedbed. l The apparatus Aforgiving effect to this invention may partake ofa number of different modiication and, briefly comprises a porous bed incommunication with a cham- -ber connected toan exhaust fan or blower.This' porous bed is formed of a screen on the upper surface of which, orbetween two lay- 'ers thereof is provided a layer ofspherical or roundedbodies of a dimension vwhich will aiford interstices through which theore will pass more' or less freely when' dry. Means are-provided fordirecting heated air for gas to the'space adjacent Ato the porous I 75.

type of s Invention.

Figure 1 is a longitudinal section of one' apparatus giving effect tothis "Io v Figure 2 is a transverse sectional elevation `of Fig. 1.

Figure 3 is a perforated bed. A

'Figure 4 is a vertical section of a modied -form of the apparatus forgiving effect to this invention. Figure 5 is a detailed sectional viewof the perforated bed used in Figure 4.

Figure 6 is a vertical section of another modified -form of apparatusfor giving effect t0 this invention.

detailed sectional view of the ratus in which the perforated bed ishoriyzontal. 'The apparatus consists of achamber A having a lire box Barranged at one end with ya communicating flue B for delivering hot airand gases into the top of the chamber A. Extending longitudinally along.the chamber A is a perforated screen C above which is adapted to move aseries ofv push conveyors D. These conveyors D are adapted to move thedamp or wet ore which is fed on to the screen C through the chute Eintermittentl forward so that an even layer of the said damp ore isspread over the screen C. This screen C is formed of perforated metal orwoven wire and upon its 'surface is provided a bed of rounded balls,pebbles, or other coarse material. This perforated bed is shown moreparticularly 1n Figure 3 consisting of, kthe perforated metal screen C uon which is superimposed pebbles or balls uponwhich the layer of ore isimposed.

This layer of spherical or rounded bodies may be balls of burnt clay,rounded silica grains or other pebbles, iron balls orA other suitablematerials for the purposeof forming a porous bed for the ore. It isessential that the balls, pebbles or other material employed for formingthis bed havel such dimensions and shape that interstices are providedthrough which the dried ore I'oan'pasa This layer of spheric-al orrounded bodies having a certain amount of mobility or restrictedmovement, any tendency to chokev or clog is avoided.

In the case of ore concentrates adapted to pass through 40 mesh screen,we have found that balls or pebbles ranging from oneeighth of an inch toonequarter of an inch diameter and forming a layer of about one inch inthickness will well answer the urpose. The screen must be coarse enougto allow the dried ore particles to ass throu h, and fine enough toretain the alls, pebb es.

,or the like.

Beneath the-screen C the chamber A is formed into areceiving box A forthe dried .ore formed with an inclined back plate A2 whereby thematerial is 4delivered into the discharge chutes F. These chutes F areprovided with control gates or doors F. Leading from this lower portionA of the chamber A is an exhaust G which is in communication with a fanor blower or other draught inducing means, whereby a continuous suctionis maintained through the perforated bed drawing the hot gases downtherethrough. At the vrear end of the chamber A, a discharge chute H(having a control door H) is provided leading from that portion of thechamber above the perforated bed whereby any lumps or coarse materialwhich do not pass through the perforated bed are withdrawn.

'the chamber A above 'nace or other source of hot ain In practice, theore is fed down continuously on to the perforated bed, and is conveyedltherealongzby means of the push conveyors D; at the same time, a currentof hot dry air and gases is directed from the furnace B through the flueB into the space of the surface of the layer of, damp ore. f 'V As acertain proportion ofthe moisture is removed, the particles of ore tendto adhere together to a lesser degree and to tricklethrough theinterstices of the perforated bed, the removal ofthe moisture `is thusaccelerated bl the movement of an increased quantity o hot air and gasesthrough the said bed. Any tendency to -choke'on clog las otherwise themoisture from the ,upper layersfiivilllbe carried down and condensed onthelow'erlayers so 'as to interfere with the porosity of the bed and.the satisfactory inductionof the air and hot gases. therethrough whichis essential to the working of the process.`

'is avoided by the restrlcted movement of Ingfthe apparatus illustratedinFigures 4 and'5, the perforated bed is in the 'forni of aquasifcylmdrical screen preferably slight- 1y tapering toform atruncated cone, Re-

:ferr-ing" to these figures, ,A is an enclosed chamber within. whichrotates a screen C* mounted u ona central. shaft K'. This-central shaftcarries a'series of radial arms K which .support the screen Cx which ispreferably formedas shown in Figure 5,

that isto' say, comprising an inner perforated screen C" andan outerperforated screen C, the space between accommodating pebbles, balls'or`other like rounded material C between the interstices of which thedried material is caused to pass. The chamber A is formed with anextension' A3 into which delivers a iue B" leading from a furand gases.Within this extension A3 is an internal sleeve J vinto Vwhich the ore isfed by the chute E from the conveyor belt E (or other source of supply)to which a hood E? is attached for excluding the draught. A screwconveyor J delivers the damp or wet ore into the interior of the screenC". The other end of the chamber A is formed with a diaphragm throughwhich the end of the screen Cc projects, more or less dividing thechamber A into twoparts so that the fine dried material passing throughthe screen is delivered into the portion A fromwhich it is withdrawn,whilst any lumps or coarsel material which do not pass through thescreen are delivered through the chute H.

The chamber A is in communication with a fan, blower or other exhaustingdevice through the opening G.

In practice, the damp or wet ore is fed down through the chute E fromthe conveyor E into the'interlial cylinder J where it is conveyed bythescrew feed J into the interior of the rotating screen C". The wet ore isthrown out in a layer upon the inside ofthe screen C". The radial arms Kon the shaft K serve to agitate and break up any lumps andevenlydistribute the said ore upon the said screen.

The hot air and gases coming in through the iue B are delivered on thesurface of the llayer of -ore and drawn through the screen to theexhaust outlet G. As the screen rotates, the balls, ebbles or the likeof which the porous be is composed are subject to a certain amount ofrestricted movement, thus avoiding any tendency to A choke or clog. Asthe moisture is removed and the material becomes dried,-it is carriedthrough th screens and between the interstices of the balls, pebbles orother like material between the screens C2 and C3.

The dried ore settles down into the lower portion A of the chamber A andmay be withdrawn from time to time, whilst anyoversize or coarse lumpsor foreign matterL which will not pass through the screen are withdrawnthrough the chute HQ Referring to F1gure- 6, the chamber A. is providedwith a horizontal screen C which 1s formed as illustrated in Fig. 1,that is to say, with alayer of pebbles, balls and such likematerial onthe surface thereof. Surrounding this screen C is an annular chamber Lcommunicating with the chamber, A above the surface of the screen `Cthrou h the ports L. The chamber .A above t e screen C )is provided witha horizontal diaphragm A. Above the screen C is mounted. a verticalshaft M having a series of rotating blades or rabbles D mounted uponarms D. Above the chamber A is a feed chute E into which the ore isdelivered from the con# veyor E and within the lower the chamber :A isprovided an ex G communicating with a fan, blower or other exhaustingdevice. The draw-off F for the 'ore is arranged vat the bottom of thechamber A anda similar draw-off H for the coarser material or lumpswhich do not pass through the screen C. The operation of this machine isthe same as that already described with regad-.t the other views.

We claim'z- 1. process for drying ores and other dried or dehydratedmaterial throug portion of aust pipe granular materials consisting 'offorming a la er of the material on a porous bed, inducing a current ofhot gases through the saidlayer andporousbed, drawingof the moisturewith the hot gases, and drawing the dried or dehydrated materialthroughthe said porous bed.

2. Aprocess for drying ores. and other granular materials consisting offorming a layer of the material on a porous bed, inducing a current ofhot gases through the said layer'and porous bed, agitating or stirvVring the layer of'material on the said por ous bed, drawing off themoisture with the hot gases, and drawing the dried or dehyldrtedmaterial through the vsaid -porous e I 3. A process for dryi g ores andother granularmaterials consimgof forming a' layer of thematerial on aporous bed, inducing a current of hot gases through the said layer andporous bed, causing the said material to progressalong the surface ofthe said porous bed,l drawing off the moisture with the hot gases, anddrawin te 90 said .porous bed. l

4. An apparatus for drying ores and other granular materials, consistingof a porous bed upon which a layer of the wet or damp` materialv isimposed and through' -which hot gases l arel drawn, characterized by thefact that the bed is of such a nature .that the 'ore is 'retained uponits surface whilst damp but asses through it when 10' dried ordehydrated. 5. An apparatus for drying ores and other granular materialswherein a layer of the damp or wet material is imposed upon the surfaceof the porous bed through which hot gases are'drawn characterized by thefact that the said be is formed o f'at least one perforated screen and alayer of pebbles, Aballs orother rounded materials,theintersticesbetween which are such as to offer 11 certain resistancetothe passage of the gases and retaining. the ore on the screen whilststill dam-p, but permitting of the passage of the ore therethrough whendried or dehyl drated.

6. Apparatus for drying ores and vother granular materials consisting ofa chamber having la rotating screen mounted therein, means for feedingthe wet or damp material 'into the interiorof the said Screen, means forsup lying hot gases into the interior of the said) screen and means fordrawing off,-Z through the said screen the said hot gases,'"'f and meansfor withdrawing the dried ore v '.from the chamber passing through thesaid 125 perforated screen.

, 7. Apparatus for/drying ores and other granular materials comprising achamber having a rotating screen mounted therein,

the wet or damp material lbeing fed into the 13 interior of thesaidsoreen and hot gas being damp or Wet materialis` retained on thedrawn through the said screen, characterized s'oreen Whilst dry materialis permitted to by the fact that the said rotating screen conpasstherethrough. 10 sists ofan inner screen and an outer screen Intestimony that we claim the foregoing 5 the space between which isfilled with balls, as our invention, We have Si ed our names.

pebbles, or other rounded materiale the in- GILB RT RIGG. tersticesbetween which are such as that WM. J. MCBRIDE.

